The Disc Phenomenon: A Technological Study of 50 Protohistoric Bronze Discs with Concentric Decoration, from the Abruzzo Region in Italy ()
1. Introduction
Discs are made of bronze, iron or both, and they were used for centuries by all the Iron Age Italic cultures, particularly of the “medium Adriatic” horizon, which also includes the Abruzzo region. For a long time, the discs were misconstrued as components of armour, however, currently, they are more widely linked to the expression of social and cultural belongings and are associated with both genders.
Before the year 2000, Tomedi classified 412 discs with concentric decoration, of bronze and bronze/iron, nearly all of them were sporadic but, in the last decades, many samples have been properly dug up, with an exclusive predominance of feminine provenience contests for those with concentric decoration. By the findings’ map (Figure 1), it is quite evident that the Abruzzo region, and particularly the Fucino plain, is the area with the most relevant concentration of discs, in general, and specifically for some typologies. All the discs in the assemblage are sporadic, but 60% of them indicate Fucino as provenience. Lacking of reference contexts, for a long time, discs retained the complex evolution of two classes of materials: the Villanovian rectangular pectorals and the “early Roman” bilobati discs (Peroni, 1961; Papi, 1990; Tomedi, 2000) . Both typologies are kardiophylax, a protection for the bust; they were a sort of rigid armours, and quite evidently, they were materials for a masculine world of warriors. On the contrary, contextual discs with concentric decoration, when gender is recognisable, they come from feminine burials, where they are generally found in couples, or more, of different diameters (Di Giandomenico, 2006) . Couples of discs were arranged over body’s abdomen and pubis and when discs were more numerous, they lay on the shoulders area (Colonna, 2007a) .
The quantification of all the sporadic bronze materials from Abruzzo in the Pigorini Museum shows that discs are the majority class among all classes of materials, and that the quantity of metals used in the MIA1 for the production of discs with concentric decoration represents about 42% of weight of the entire inventory (Mascelloni, 2010) .
Discs with concentric decoration refer to fertility rites and they may be associated with some kinds of sun cult, difficult to establish if of Nordic origin as Colonna (2007a) suggests, but what is utterly important for this research is that, in the Protohistory of central Italy, women played a primary role inside the clan. To summarize, discs with concentric decorations were linked to the feminine sphere of influence inside the Italic societies.
The research proposes a diachronic analysis of samples considering the hypothesis that discs with concentric decoration have both independent origins and different functions from either armour pectorals or figurative samples.
In order to process discs in all these aspects, their dress code has been investigated through the study of decorations, suspension systems and reparations.
2. Methodology
The whole assemblage includes 50 discs with concentric decorations and 4
figurative samples2. Research focuses on discs with concentric decoration, and figurative samples are used for data comparison.
All the discs were technologically and traceologically analysed by optical microscope, instead, chemical characterization by XRF-ED was performed only on 27 of them3.
Since most of the discs appear frequently fixed during their life time, particular attention is given to chemical compositions and technologies of various constituent elements or parts of reparation, in order to compare data either inside the same artefact or among those showing similar interventions.
All the data were statistically analysed.
3. Result and Discussion
Discs typologies are defined by different combinations of decorative technics. Earliest samples are conical or slightly convex-thick sheets of bronze with strictly geometric decorations and with bronze or lead as constituent elements. In the late figurative samples, instead, bronze sheets are thinner and flatter and systematically back supported by iron sheets.
There are five geometric discs which do not belong to any typological groups and they are called simply “geometric” (Figure 2).
Dated to the X-IX century BC (Figure 2), the Aielli discs are thick sheets decorated only by dots, normally drilled but sometimes engraved. The Aielli discs present strict analogies with 7 iron drilled discs from the Fossa Necropolis, not far from Fucino (Figure 3).
Both typologies are drilled and the Fossa discs are always coupled and arranged over abdomen and pubis of the dead as well. They come from 4 different
feminine burials (Cosentino et al., 2001) . The Fossa discs had no relevant iron continuation4; discs were made for long lasting and most likely, iron did not satisfy the expectations, however their most relevant features were peculiar to the bronze discs with concentric decoration as well. It is also noticeable that the only concentric decoration disc of bronze showing of iron constituent components evidence, is a drilled sample (85251)5; the disc presents the fingerprint of an iron cerclage all along the rim (Figure 5).
As already mentioned, the formula of discs with concentric decoration summarizes formal, artistic and symbolic aspects that highly refer to astral cults. Concentric decoration follows an obsessive and rigid cyclicity. 39 discs out 50 present astral symbols at the centre of the umbone (the central area): 26, a star; 10, a sun; and 2, both symbols. Moreover, a profusion of rays and meanders reminds the “sun wheel” symbology.
3.1. Suspension System
From the holes disposition in the centre and long the discs’ rim, have been hypothesised four-hole patterns for their suspension (Figure 11):
➢ Centre: Only a central hole, mainly for small sized discs;
➢ Centre + n: The central hole plus a number of holes along the rim;
➢ Centre + 2 + n: The major group, the central hole and 2 adjacent holes plus a number of adjacent holes in the opposite side along the rim. Except for one case6, all the AF group belongs to the centre + 2 + n class (Figure 4);
➢ Rim: Only a variable number of holes along the rim, exclusive to the figurative typologies.
Some of them have riveted studs or show their fingerprints, others completely lack them. Whenever studs are in situ, they support rings or loop plates on the back.
By the position of the holes and the study of the surrounding areas by microscope observation, can be inferred five suspension systems (Figure 11):
➢ Ring: By a central ring on the back. In a drilled disc (85494)7, the central rivet, of a lead rich alloy, doesn’t present any ring on the back and no evidence of breakage (Figure 5). Maybe drilled discs could have been suspended also by using drilling holes;
➢ Iron: By iron constituent elements. Two discs of the figurative samples and the drilled disc 85494 belong to this group (Figure 5)8. The drilled disc presents two large gaps on the body and, in this case as well, suspension by drilling holes can be suggested;
➢ Stud: This group gathers discs where all the holes support studs or show fingerprints of them;
➢ Chain: The group gather discs where all the holes, except the central one, show to have never supported studs. The holes elongated shape suggests chains or hooks as direct support;
➢ Studs/chain: These are discs where both holes are present. Except for one case, all the discs of this group show a hole pattern “centre + 2 + n” with 2 holes for studs opposite to a variable number of holes for chains.
Certainly, disc suspension presupposed a slow gesticulation and didn’t leave much freedom of movement. Perhaps, many discs were used also for better balancing. In any case, disc dressing must have been very tiring.
All the discs show evidences of a long utilization time. Rims are worn out and variously deformed, mostly in correspondence with holes. On the other hand, more than 22% of discs are unbroken and 9% of them with a sole fracture on the rim (Figure 9).
Fractures are associated to the sheet working quality, to the decorators’ ability and obviously to the suspension system.
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Figure 4. Ratio between hole patterns and typologies of discs. Top right: disc 53833 (see note 6).
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Figure 5. Disc 85251 and disc 85494 (Pigorini Museum).
Generally, connection between fractures and disc typologies shows that drilled samples have the worst degree of conservation (Figure 6). The hard working, connected to the annealing, sheet shape forming and decoration, seem to be the main causes of damage. Fractures follow the bases of the umbone embossing or the decoration lines (Figure 7).
Some fractures seem to have been occurred directly during the disc production, or immediately after, as in the case of the Casacanditella drilled sample 85493 which shows a fracture long a shrinking line, perpendicular to the umbone base (Figure 8). The 3 rivets of this almost invisible reparation probably sustained a little plate, now disappeared.XRF analysis of one of the rivets indicates that its composition is unusually consistent with the compositions of the other disc components.
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Figure 6. Ratio between fractures and typologies of discs.
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Figure 8. Reparation details and XRF analysis of disc 85493 components.
The Aielli discs present strict analogies with the Fossa samples and both of them served the same function linked to the feminine world. The reason why disc technology rised by iron is the most intriguing question raised by this research, but presently, the available data don’t allow an exhaustive answer to the question. It is clear though that the disc phenomenon was utterly important for these communities to urge a technological change. More experimental phases started, soon after the bronze solution was found.
Casacanditella group is characterised by the fretwork, technically and stylistically more complex and evolved than in the Aielli-type discs, and also variously combined with the entire range of technical choices of full lamina decoration. Casacanditella discs are massive sheets with big thickness. They normally present circular decorated plates covering and supporting the umbone, where embossing is particularly pronounced and therefore the disc easily cracks.
Casacanditella discs appear to be earlier than Civitaluparella, Collarmele or AF ones. Inone AF sample, there are fragments of a circular plate, used as reinforce, but it is only a late case; once technology improves, plates disappear.
The discs of the Civitaluparella type present a deep decoration technique on thick plates, and they totally lack the embossing technique.
Collarmele and Alba Fucens (AF) typologies share the same decoration techniques but the AF discs introduce figurative subjects in concentric registers, in line with the spread of the orientalizzante style.
AF discs have the best degree of conservation with two third of them in the unbroken and rim 1 fracture classes (Figure 6). They have manly big diameters. Out of the 55 AF discs we know (Tomedi, 2000) , only four samples have low diameters; two of them are in this assemblage, one “geometric” disc (53753) and the recycled umbone 53833 (Figure 4)9. On the contrary, about 70 % of Collarmele discs have low diameters. Perhaps it was common that Collarmele small discs accompanied AF bigger ones and, in general, that different typologies of discs were used together.
AF typology achieved a sort of balance regarding technology with ideal thicknesses ranging between 9 and 11 millimetres and diameters between 22 and 26 cm. Disc analysis suggests that AF typology represents an arrival point of disc production after a long experimental period and technological changes (Figure 2).
3.2. Reparations
About 25% of discs show to be repaired in their life time in 1 or 2 points (Figure 9). Reparations fix fractures along the rim, or around the umbone, with small plates supported by two or more bronze rivets, by iron or mixed.
Five discs present a real or latent trapezoidal gap on the rim and one of them (3501) a double hatch that preludes its occurrence (Figure 10). All the 5 samples are in a bad state and present more than a reparation, so it is possible that they come from one or more hoards where they were stored for chemical and physical recycling.
3.3. Chemical Composition
XRF analysis identifies 7 elements: Cu, Sn, Pb, As, Ag, Sb, and Fe.
Analyses have been taken on: 27 sheets; 2 loop plates; 7 nails; 1 plate and 1 rivet of two similar reparations from two different discs; and 1 rivet from 3 discs where plates were by iron (Figure 11, Table 1).
Except for two cases where lead was not detected, all the discs and their components have a ternary (tin/lead) bronze alloy composition with copper ranging between about 94% in one sheet and 73% in one rivet (Table 1).
The discs bulk is contained in ranges from 6% to 12% of tin and from 1% to 4% of lead (Figure 8).
As, Ag, and Sb, as trace elements, are rarely coupled, and never together; these facts suggest three groups of composition (Figure 12). All the Alba Fucens(AF) discs belong to the silver group, except for two samples from Menaforno. The bulk of the Casacanditella discs belongs to this group too. Frequently, iron is also present in association with silver.
More interesting data refer to finding associations of discs. In 6 out of 9 cases, disc associations are notably consistent in trace element composition. All the discs are sporadic, without any indication of finding contexts except sometimes about the sites; they probably are the result of fortuitous finds or illegal searches. Hoping that when they were sold, the discs of the various lots came from the same contexts, it can be conjectured that they shared the same depositions. In fact, the discs of the various lots have very similar patinas10.
More accurate investigations and more analysis points on selected discs could better define composition groups. On the other hand, the scarce consistence in composition of the reparation parts suggests that local workshops largely adopted metal recycling.
4. Conclusion
The disc phenomenon is still to be explored, considering the opportunity to extend and compare archaeometric data with new research lines: the recent contextual findings in the Cretaro-Chiusa Necropolis of Avezzano, the main town of the Fucino area, where a number of bronze discs with concentric decoration were found in fourteen female burials out of a total of eighteen graves (Ceccaroni, 2010) ; and the new interpretation of two lots of—alleged Umbrian—bronze materials, acquired at the beginning of the 1900s by the Archaeological Museum of Florence, which include at least 17 concentric decoration discs, between wholes and fragments, most likely of Abruzzo origin (Colonna, 2007b) .
Traceological and chemical aspects suggest that local workshops operated in the Fucino area with their own strategies either compensating for the difficulties of acquiring raw materials or adapting technology to commissions. At the same
time, technology and chemistry of discs show that production was performed by highly specialized bronze workshops, hardly to conceive in protohistoric Abruzzo at the state of knowledge.
On the other hand, some clues indicate an early occurrence in Abruzzo of metallurgical activity dedicated to the experimentation and production of iron artefacts. First of all, the strict analogies between the Aielli bronze discs and the
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Figure 12. Composition groups of the disc sheets. F = Figurative discs.
oldest Fossa iron samples. Fossa discs still now represent a unicum, and as such it seems difficult to trace them elsewhere. Moreover, iron reparations of very early bronze Aielli discs, in connection with iron occurrence as a constituent element in late figurative bronze samples, suggest, at least for the Middle Iron Age, two different metallurgical traditions between local workshops and bronze production centres.
Except for the Cretaro sample (see note 4), the Fossa discs seem to have no relevant continuation in iron, discs were made for long lasting and iron did not satisfy the expectations, but their most relevant features are peculiar also to the bronze discs, showing an amazing investment in symbolic representations.
On the general point of view, this research strongly suggests that production of discs with concentric decoration was a primary need for the Italic societies of the central Italy, so much as to stimulate and encourage experimentation with both techniques and materials.
Acknowledgements
Prof. Giorgio Cerichelli and Prof. Aldo Domenicano, Department of CCE Materials, Aquila University; Prof. Stefano Ridolfi, Art Mensurae, Rome; Prof. Claudio Giardino, University of Arkansas, Rome; Dr.ssa Anna Candida Felici, Department of Energetic, Rome University; Dr. Mario Amore, Ethnographic and Prehistoric Museum L. Pigorini, Rome; Dr.ssa Mafalda Cipollone, National Archaeological Museum of Umbria, Perugia; Dr.ssa Stefania Montanaro, Prehistoric Museum of Celano (AQ).
NOTES
1MIA: Middle Iron Age. In Italian chronology, it is most frequently “EtàOrientalizzante ed Arcaica”.
227 discs, part of the Bellucci Collection, owned by the Perugia Archaeological Museum; 26 discs of the Pigorini Museum of Rome; and 1 unpublished disc of the Ventura Collection, owned by the Celano Prehistorical Museum. Four-digit inventory for the Perugia Museum and five-digit inventory for the Pigorini.
3The 26 discs of the Pigorini Museum and the disc of the Celano Museum.
4A drilled iron disc, in poor condition, recently emerged from tomb 32 of the necropolis in locality Cretaro-Chusa, Avezzano (Ceccaroni, 2010) .
5Casacanditella disc n. 85251 of the Pigorini Museum.
6AF 53833 of the Pigorini Museum. It is probably one—trimmed and shaped—umbone of a bigger disc.
7Casacanditella disc 85494 of the Pigorini Museum.
8Two Alfadena discs: n. 61835 and n. 61836 and the Casacanditella disc n. 85251 of the Pigorini Museum.
9Why they have been catalogued as Alba Fucens (AF) is a good question.
10The study of the patinas and chemical analysis were only possible for the materials of the Pigorini Museum. Unfortunately, the choice of the restoration lab of the Archaeological Museum of Perugia not to remove the residues of organic material from the disc deposition and not to clean and protect them in any way, has made it impossible to carry out in-depth studies on the materials.